An Edible History of Humanity (23 page)

When scientists in Britain and other countries had tried to replicate the Haber-Bosch process themselves during the war, they
had been unable to do so because crucial technical details had been omitted from the relevant patents. These patents were
confiscated after the war, and BASF’s plants were scrutinized by foreign engineers, leading to the construction of similar
plants in Britain, France, and the United States. During the 1920s the process was refined so that it could use methane from
natural gas, rather than coal, as the source of hydrogen. By the early 1930s the Haber-Bosch process had overtaken Chilean
nitrates to become the dominant source of artificial fertilizer, and global consumption of fertilizer tripled between 1910
and 1938. Having relied on soil microbes, legumes, and manure for thousands of years, mankind had decisively taken control
of the nitrogen cycle. The outbreak of the Second World War prompted the construction of even more ammonia plants to meet
the demand for explosives, which meant that there was even more fertilizer-production capacity available after the war ended
in 1945. The stage was set for a further dramatic increase in the use of artificial fertilizer. But if its potential to increase
food production was to be exploited to the full, new seed varieties would also be needed.

The availability of artificial fertilizer allowed farmers to supply much more nitrogen to their crops. For cereals such as
wheat, maize, and rice, this produced larger, heavier seed heads, which in turn meant higher yields. But now that they were
no longer constrained by the availability of nitrogen, farmers ran into a new problem. As the use of fertilizer increased
the size and weight of the seed heads, plants became more likely to topple over (something farmers call “lodging”). Farmers
had to strike a balance between applying plenty of fertilizer to boost yield, but not so much that the plants’ long stalks
were unable to support the seed heads. The obvious solution was to switch to short, or “dwarf” varieties with shorter stalks.
As well as being able to support heavier seed heads without lodging, dwarf varieties do not waste energy growing a long stalk,
so more energy can be diverted to the seed head. They therefore boost yield in two ways: by allowing more fertilizer to be
applied, and by turning applied nutrients more efficiently into useful grain, rather than useless stalk.

During the nineteenth century, dwarf varieties of wheat, probably descended from a Korean variety, had been developed in Japan.
They greatly impressed Horace Capron, the United States’ commissioner of agriculture, who visited Japan in 1873. “No matter
how much manure is used . . . on the richest soils and with the heaviest of yields, the wheat stalks never fall down and lodge,”
he noted. In the early twentieth century these Japanese dwarf varieties were crossed with varieties from other countries.
One of the resulting strains, Norin 10, was a cross between Japanese wheat and two American varieties. It was developed in
Japan, at the Norin breeding station, and was transferred to the United States after the Second World War. Norin 10 had unusually
short, strong stems (roughly two feet tall, rather than three feet), and responded well to heavy applications of nitrogen
fertilizer. But it was susceptible to disease, so agronomists in different countries began to cross it with local varieties
in order to combine Norin 10’s dwarf characteristics with the pest resistance of other varieties. This led to new, high-yielding
varieties of wheat suitable for use in particular parts of the world. In industrialized countries where use of nitrogen fertilizer
was growing quickly, the new varieties descended from Norin 10 made possible an impressive increase in yield. By this time
new, high-yielding varieties of maize had also become widespread, so that during the 1950s the U.S. secretary of agriculture
complained that the country was accumulating “burdensome surpluses” of grain that were expensive to store.

When it came to the developing world, one man did more than anyone else to promote the spread of the new dwarf varieties:
Norman Borlaug, an American agronomist. He went to Mexico in 1944 at the behest of the Rocke feller Foundation, which had
established an agricultural research station there to help to improve poor crop yields. The foundation had concluded that
boosting yields was the most effective way to provide agricultural and economic assistance, and reduce Mexico’s dependence
on grain imports. Borlaug was put in charge of wheat improvement, and his first task was to develop varieties that were resistant
to a disease called stem rust, which was a particular problem in Mexico at the time: It reduced Mexico’s wheat harvest by
half between 1939 and 1942. Borlaug created hundreds of crossbreeds of local varieties, looking for strains that demonstrated
good resistance to stem rust and also provided strong yields. Within a few years he had produced new, resistant breeds with
yields 20 to 40 percent higher than the traditional varieties in use in Mexico.

Mexico was an excellent place to carry out such research, Borlaug realized, because one wheat crop could be grown in the highlands
in the summer, and another in the lowland desert in the winter. He developed a new system called “shuttle breeding,” in which
he carried the most promising results from one end of the country to another. This broke the traditional rule that plants
should only be bred in the area in which they would subsequently be planted, but it sped up the breeding process, since Borlaug
could produce two generations a year rather than one. His rule-bending also had another, unanticipated benefit: In order to
thrive as both summer and winter crops, the resulting varieties could not afford to be fussy about the difference in the number
of hours of daylight between the two seasons. This meant their offspring could subsequently be cultivated in a wide range
of different climates.

In 1952 Borlaug heard about the work being done with Norin 10, and the following year he received some seeds from America.
He began to cross his new Mexican varieties with Norin 10, and with a new variety that had been created by crossing Norin
10 with an American wheat called Brevor. Within a few years he had developed new wheat strains with insensitivity to day length
and good disease resistance that could, with the use of nitrogen fertilizer, produce more than twice the yield of traditional
Mexican varieties. Borlaug wanted to make further improvements, but curious farmers visiting his research station were taking
samples of his new varieties and planting them, and they were spreading fast. So Borlaug released his new seeds in 1962. The
following year, 95 percent of Mexico’s wheat was based on one of Borlaug’s new varieties, and the wheat harvest was six times
larger than it had been nineteen years earlier when he had first arrived in the country. Instead of importing 200,000 to 300,000
tons of wheat a year, as it had done in the 1940s, Mexico exported 63,000 tons of wheat in 1963.

Following the success of his new high-yielding dwarf wheat varieties in Mexico, Borlaug suggested that they could also be
used to improve yields in other developing countries. In particular, he suggested India and Pakistan, which were suffering
from poor harvests and food shortages at the time and had become dependent on foreign food aid. Borlaug’s suggestion was controversial,
because it would mean encouraging farmers to grow wheat rather than indigenous crops. Borlaug maintained, however, that since
wheat produced higher yields and more calories, his new dwarf wheat varieties presented a better way for South Asian farmers
to take advantage of the advent of cheap nitrogen fertilizer than trying to increase yields of indigenous crops. Monkombu
Sambasivan Swaminathan, an Indian geneticist who was an adviser to the agriculture minister, invited Borlaug to visit India,
and Borlaug arrived in March 1963 and began promoting the use of his Mexican wheat. Some small plots were planted, and they
produced impressive results at the following year’s wheat harvest: With irrigation and the application of nitrogen fertilizer,
the yields were around five times that of local Indian varieties, which typically produced around one ton per hectare. Swaminathan
later recalled that “when small farmers, who with the help of scientists organised the National Demonstration Programme, harvested
over five tons of wheat per hectare, its impact on the minds of other farmers was electric. The clamour for seeds began.”

Another impressive harvest in early 1965 prompted the Indian government to order 250 tons of seed from Mexico for further
trials. But wider adoption of the new seeds was held back by political and bureaucratic objections. A turning point came when
the monsoon, which normally occurs between June and September, failed in 1965. This caused grain yields to fall by nearly
one fifth and made India even more dependent on foreign food aid. The government sent officials to Mexico to place an order
for eighteen thousand tons of the new wheat seeds—enough to sow around 3 percent of India’s wheat-growing areas. As the ship
carrying the seeds departed for Bombay, war broke out between India and Pakistan, diverting attention from the food crisis
gripping the region. And by the time the seeds were being unloaded in September, it was apparent that the monsoon had failed
for a second year.

As with Thomas Malthus’s predictions nearly two centuries earlier, the technologies that would disprove these gloomy predictions
were already quietly spreading. Following the introduction of Borlaug’s high-yield varieties from Mexico, wheat yields in
India increased from twelve million tons in 1965 to nearly seventeen million tons in 1968 and twenty million in 1970. The
harvest in 1968 was so large that schools had to be closed in some areas so that they could be used for grain storage. India’s
grain imports fell almost to zero by 1972, and the country even became an exporter for a while during the 1980s. Further improvements
in yields followed in subsequent years as Indian agronomists crossed the Mexican varieties with local strains to improve disease
resistance. India’s wheat harvest reached 73.5 million tons in 1999.

Norman Borlaug’s early success with high-yield dwarf varieties of wheat, meanwhile, had inspired researchers to do the same
with rice. The International Rice Research Institute (IRRI), based in the Philippines and funded by the Rocke feller and Ford
foundations, was established in 1960. Borlaug’s shuttle-breeding approach was adopted to speed up the development of new varieties.
As with wheat, researchers took dwarf varieties, many of them developed in Japan, and crossed them with the local varieties
planted in other countries. In 1966 researchers at the IRRI created a new variety, called IR8, by crossing a Chinese dwarf
variety (itself derived from a Japanese strain) with an Indonesian strain called Peta. At the time, traditional strains of
rice produced yields of around one ton per hectare. The new variety produced five tons without fertilizer, and ten tons when
fertilizer was applied. It became known as “miracle rice” and was quickly adopted throughout Asia. IR8 was followed by further
dwarf strains that were more disease resistant and matured faster, making it possible to grow two crops a year for the first
time in many regions.

In a prescient speech in March 1968, William Gaud of the United States Agency for International Development had highlighted
the impact that high-yield varieties of wheat were starting to have in Pakistan, India, and Turkey. “Record yields, harvests
of unprecedented size and crops now in the ground demonstrate that throughout much of the developing world—and particularly
in Asia—we are on the verge of an agricultural revolution,” he said. “It is not a violent red revolution like that of the
Soviets, nor is it a white revolution like that of the Shah of Iran. I call it the green revolution. This new revolution can
be as significant and as beneficial to mankind as the Industrial Revolution of a century and a half ago.” The term “green
revolution” immediately gained widespread currency, and it has remained in use ever since.